: an elementary particle that is identical with the nucleus of the hydrogen atom, that along with the neutron is a constituent of all other atomic nuclei, that carries a positive charge numerically equal to the charge of an electron, and that has a mass of 1.673 × 10−27 kilogram
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Once the universe expanded and cooled enough (down to around 3000 Kelvin (approximately 4,900 degrees Fahrenheit or 2,700 degrees Celsius), electrons were able to bind with protons and form the first neutral atoms of hydrogen and helium, the first elements.
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Robert Lea, Space.com, 18 Mar. 2025
Electrons gently tug on protons in the lattice, drawing them inward to create an excess of positive charge.
—Charlie Wood, WIRED, 12 Jan. 2025
Mars has faint proton auroras of Mars, and Uranus has faint ultraviolet emissions.
—Jamie Carter, Forbes.com, 26 Mar. 2025
That is because, as Earth rotates, the direction of the proton beams generated for particle collisions in the powerful particle accelerator changes.
—Robert Lea, Space.com, 21 Feb. 2025
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Robert Lea, Space.com, 18 Mar. 2025
Electrons gently tug on protons in the lattice, drawing them inward to create an excess of positive charge.
—Charlie Wood, WIRED, 12 Jan. 2025
Mars has faint proton auroras of Mars, and Uranus has faint ultraviolet emissions.
—Jamie Carter, Forbes.com, 26 Mar. 2025
That is because, as Earth rotates, the direction of the proton beams generated for particle collisions in the powerful particle accelerator changes.
—Robert Lea, Space.com, 21 Feb. 2025
See All Example Sentences for proton
Cite this Entry
“Proton.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/proton. Accessed 20 Apr. 2025.
Copy CitationKids Definition
proton
noun
pro·ton
ˈprō-ˌtän 
: an atomic particle that occurs in the nucleus of every atom and carries a positive charge equal in size to the negative charge of an electron
Medical Definition
proton
noun
pro·ton
ˈprō-ˌtän
: an elementary particle that is identical with the nucleus of the hydrogen atom, that along with neutrons is a constituent of all other atomic nuclei, that carries a positive charge numerically equal to the charge of an electron, and that has a mass of 1.673×10−24 gram
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